In recent years, the telecommunication industry has seen an increase in personal communication systems which provide the consumer with wireless voice and data transmission. Wireless information transmission requires the provision of separate send and receive antennas operating at about 2,000 MHz frequency. These antennas must be positioned in an elevated manner and orientated to optimize signal reception and transmission.
For obvious reasons, it is desirable to avoid the construction of a dedicated tower for the antennas. Such structures are costly and have a high degree of impact upon the surrounding environment, particularly if located within a residential area. Pre-existing structures would therefore provide a more practical solution for mounting of the antenna. One such structure is the utility power transmission tower.
While electric power transmission towers could provide an economic and environmental advantage if adapted to function as an antenna support, such towers are not without problems. First, although wireless communication antennas may function with a six foot separation distance between the send and receive antennas, a separation distance of ten feet is highly preferred. Minimum distances must also be maintained from the high voltage conductors supported by the tower. These preferred distances are difficult to obtain at the top of the tower, an area already crowded not only by the high tension lines but also spars and related structural members. Since it is imperative the electric power transmission tower accommodate correctly spaced antennas, the antenna mount employed must be adapted to fit within the upper structures of the tower as well as provide the critical antenna spacing distances.
In addition, it is preferred to fit the top of the tower with a compliment of antennas covering a full 360.degree.. Since the antennas are arranged in groups of send and receive antennas, this requires three separate sets of antennas oriented 120.degree. apart from each other. Again, the structure of the tower itself may prevent this preferred orientation. In older tower constructions, the frame of the tower comprises four separate legs oriented 90.degree. apart. If each group of antennas is mounted to a separate leg, the mount must allow for lateral adjustment of the antenna groups.
Because the clearances at the top of the tower are tight, assembly of the mounting bracket to the tower is a concern. A preferred bracket will have a compact, relatively low weight design that enables the workers to lift the cumbersome bracket without the need for heavy construction equipment or the drilling holes into the tower, therefore minimizing the likelihood of contact against a live high voltage line. The relatively large dimensions of the bracket mandate in situ fabrication. Thus, a preferred bracket design would allow for portions of the bracket to be assembled on the ground adjacent the tower site, and lifting of the subassembly into position using a pulley or other simple hoist prior to attachment to the tower.
Following attachment of the antenna group to the tower, it is of course necessary to orient the antennas if they are to be operable. A bracket permitting maximum adjustability is preferred since utility tower construction varies widely.
In view of the above, a need has existed in the art for an antenna mounting bracket and assembly that addresses each of the above noted problems.